This research addresses two distinct types of knowledge representations- -active and latent--and their potential role in infants' task-dependent behavior with hidden objects. Infants can appear precocious or limited in almost any ability depending on the task administered to them. For example, infants as young as 3.5 months show an apparent sensitivity to the continued existence of hidden objects in visual habituation studies, yet infants fail to manually retrieve hidden objects until around 9 months, independent of any motor or problem-solving deficits. This research explores the possibility that infants use latent representations to recognize unusual events in visual habituation studies, but require later developing active representations to retrieve occluded objects. Active representations take the form of sustained neuronal firing, while latent representations take the form of changes in firing thresholds or neuronal connections that affect neuronal activity only in subsequent processing. The proposed studies are adapted from tasks used with non-human primates, in which the neural mechanisms and behavioral manifestations of active and latent representations are relatively well understood. The studies have two specific aims. First, they investigate infants' biases and capacities for forming active and latent representations. Second, they attempt to identify the potential contributions from active and latent representations to infants' task-dependent behavior with hidden objects. Study 1 tests the hypothesis that infants, like non- human primates, are biased to form latent rather than active representations when either will suffice for the task at hand. Study 2 tests the hypothesis that infants, like non-human primates, possess some capacity for forming active representations that may be obscured by their bias for latent representations. Task-dependent behaviors may provide a window onto the psychological and neural bases of development, so results from these studies may inform theory and its application to both typical and special populations.